Ultrasonic diagnostic imaging system with automatic control of penetration, resolution and frame rate

ABSTRACT

An ultrasonic diagnostic imaging system and method are presented in which the balance between image resolution and frame rate (Res/Speed) and the balance between image resolution and penetration (Pen/Gen/Res) are automatically adjusted in response to image content. A motion detector analyzes the relative motion between successive images. If the motion content is relatively high, the imaging parameters are changed in favor of relatively greater frame rate and reduced resolution. A low motion content causes the opposite adjustment. The electronic noise between successive images is also computed with a relatively high noise content (low correlation) in the far field resulting in an adjustment to penetration as by lowering the transmit frequency. A relatively low noise content causes an adjustment in favor of increased resolution.

This invention relates to medical diagnostic imaging systems and, inparticular, to diagnostic imaging systems which automatically controlultrasonic imaging for optimal tissue penetration, imaging frame rate,and image resolution.

Ultrasonic diagnostic imaging applications can differ widely in theimaging conditions encountered. When imaging the fetal heart forinstance a high frame rate of display is required to accurately imagethe detail of a rapidly beating heart. In other applications such as thediagnosis of tumors in the liver, a high frame rate is not necessary buta high image quality (resolution) is generally preferred. In some casesthe pathology being diagnosed may be deep within the patient's body. Inother cases the pathology may be just beneath the skin. These widelydiffering conditions mean that the sonographer frequently has to changea wide variety of settings on the ultrasound system in order to acquirethe best images for a given examination. It would be desirable tominimize the number of ultrasound system settings which need to bemanipulated in order to set up the system for a new exam. In particular,it would be desirable for many of the manual settings of an ultrasoundsystem to be automated when possible so that the ultrasound system wouldautomatically optimize the operational settings of the system on thebasis of the examination being performed.

In accordance with the principles of the present invention, anultrasonic diagnostic imaging system is described which automates two ofthe most frequently used user settings, the Res/Speed control and thePen/Gen/Res control. The Res/Speed control adjusts the trade-off betweenimage quality (resolution) and frame rate (speed) by varying imagingparameters such as image line density, multiline order, and number offocal zones. The Pen/Gen/Res control adjusts the trade-off between imageresolution and the depth of penetration of ultrasound through control ofimaging parameters such as the transmit and receive frequencies. In anillustrated embodiment the setting of these controls is automated bysensing the amount of motion and/or noise in the anatomy being imaged.In response to the sensed image motion and/or noise, the relevant imageparameters are automatically varied to obtain images which are asensible balance of these competing factors.

In the drawings:

FIG. 1 illustrates in block diagram form an ultrasonic diagnosticimaging system constructed in accordance with the principles of thepresent invention.

FIG. 2 illustrates an implementation of a Res/Speed control on anultrasound system and a Pen/Gen/Res control on an ultrasound system.

FIG. 3 illustrates an ultrasound sector image which has been dividedinto image sub-regions for motion analysis.

FIG. 4 illustrates a methodology for analyzing motion in successiveultrasound images.

FIG. 5 illustrates the correlation of types of information in successiveultrasound images.

Referring first to FIG. 1, an ultrasonic diagnostic imaging systemconstructed in accordance with the principles of the present inventionis shown in block diagram form. An ultrasonic scanhead 12 includes anarray 14 of ultrasonic transducers that transmit and receive ultrasonicpulses. The array may be a one dimensional linear or curved array fortwo dimensional imaging, or may be a two dimensional matrix oftransducer elements for electronic beam steering in three dimensions.The ultrasonic transducers in the array 14 transmit ultrasonic energyand receive echoes returned in response to this transmission. A transmitfrequency control circuit 20 controls the transmission of ultrasonicenergy at a desired time and at a desired frequency or band offrequencies through a transmit/receive (“T/R”) switch 22 coupled to theultrasonic transducers in the array 14. The times at which thetransducer array is activated to transmit signals may be synchronized toan internal system clock (not shown), or may be synchronized to a bodilyfunction such as the heart cycle, for which a heart cycle waveform isprovided by an ECG device 26. When the heartbeat is at the desired phaseof its cycle as determined by the waveform provided by ECG device 26,the scanhead is commanded to acquire an ultrasonic image. The ultrasonicenergy transmitted by the scanhead 12 can be relatively high energy(high mechanical index or MI) which destroys or disrupts contrast agentin the image field, or it can be relatively low energy which enables thereturn of echoes from the contrast agent without substantiallydisrupting it. The frequency and bandwidth of the ultrasonic energygenerated by the transmit frequency control circuit 20 is controlled bya control signal f_(tr) and the times at which individual elements inthe array are actuated to steer and focus an ultrasonic beam in adesired direction is controlled by a control signal T_(st). Both controlsignals are generated by a central controller 28.

Echoes from the transmitted ultrasonic energy are received by thetransducers in the array 14, which generate echo signals that arecoupled through the T/R switch 22 and digitized by analog to digital(“A/D”) converters 30 when the system uses a digital beamformer. Analogbeamformers may also be used. The A/D converters 30 sample the receivedecho signals at a sampling frequency controlled by a signal f_(s)generated by the central controller 28. The desired sampling ratedictated by sampling theory is at least twice the highest frequency ofthe received passband, and might be on the order of at least 30-40 MHz.Sampling rates higher than the minimum requirement are also desirable.

The echo signal samples from the individual transducers in the array 14are delayed and summed by a beamformer 32 to form coherent echo signalsin a desired beam steering direction specified by a control signalR_(st). The digital coherent echo signals are then filtered by a digitalfilter 34. In this embodiment, the transmit frequency and the receiverfrequency are individually controlled so that the beamformer 32 is freeto receive a band of frequencies which is different from that of thetransmitted band. The digital filter 34 bandpass filters the signals,and can also shift the frequency band to a lower or baseband frequencyrange. The digital filter could be a filter of the type disclosed inU.S. Pat. No. 5,833,613.

Filtered echo signals from tissue are coupled from the digital filter 34to a B mode processor 36 for conventional B mode processing. The B modeimage may also be created from microbubble echoes returning in responseto nondestructive ultrasonic imaging pulses.

Filtered echo signals of a contrast agent, such as microbubbles, arecoupled to a contrast signal processor 38. The contrast signal processor38 preferably separates echoes returned from harmonic contrast agents bythe pulse inversion technique, in which echoes resulting from thetransmission of multiple pulses to an image location are combined tocancel fundamental signal components and enhance harmonic components. Apreferred pulse inversion technique is described in U.S. Pat. No.6,186,950, for instance. The detection and imaging of harmonic contrastsignals at low MI is described in U.S. Pat. No. 6,171,246.

The filtered echo signals from the digital filter 34 are also coupled toa Doppler processor 40 for conventional Doppler processing to producevelocity and power Doppler signals. The outputs of these processors maybe displayed as planar images, and are also coupled to a 3D imagerendering processor 42 for the rendering of three dimensional images,which are stored in a 3D image memory 44. Three dimensional renderingmay be performed as described in U.S. Pat. No. 5,720,291, and in U.S.Pat. Nos. 5,474,073 and 5,485,842, all of which are incorporated hereinby reference.

The signals from the contrast signal processor 38, the B-mode processor36 and the Doppler processor 40, and the three dimensional image signalsfrom the 3D image memory 44 are coupled to a Cineloop® memory 48, whichstores image data for each of a large number of ultrasonic images. Theimage data are preferably stored in the Cineloop memory 48 in sets, witheach set of image data corresponding to an image obtained at arespective time. The sets of image data for images obtained at the sametime during each of a plurality of heartbeats are preferably stored inthe Cineloop memory 48 in the same way. The image data in a group can beused to display a parametric image showing tissue perfusion at arespective time during the heartbeat. The groups of image data stored inthe Cineloop memory 48 are coupled to a video processor 50, whichgenerates corresponding video signals for presentation on a display 52.The video processor 50 preferably includes persistence processing,whereby momentary intensity peaks of detected contrast agents can besustained in the image, such as described in U.S. Pat. No. 5,215,094.

In accordance with the principles of the present invention amotion/noise processor 46 is provided to detect the motion of objectsand/or noise in the image field. This is done in the illustratedembodiment by a correlation process such as a Pearson's correlationwhich will be discussed more fully below. The criteria against which theresults of the correlation process are compared are determined by thesetting of either a Res/Speed control or a Pen/Gen/Res control or bothby user adjustment of a control on a user interface 150 as discussedbelow. The results of the detection of motion and/or noise in the imagefield are used to automatically adjust the settings of either or both ofthe Res/Speed control and the Pen/Gen/Res control. The adjustmentsoptimize the operation of the ultrasound system to provide clearer,better resolved images by adjustment of imaging parameters in responseto the outcome of the detection of motion and/or noise.

Examples of a Res/Speed control and a Pen/Gen/Res control are shown inFIG. 2. While these controls may be hardware knobs or sliders on acontrol panel, in this embodiment the controls are display controlsgenerated by software on the screen of the ultrasound display 52. Thecontrols may be displayed as dials or meters or other graphics displayedin various shapes and colors, and may have either qualitative orquantitative settings. In this embodiment both are qualitative bardisplays 60. The Res/Speed control 62 is variable between “Res” (maximumresolution) and “Speed” (maximum frame rate) and proportions of thesemaximum settings therebetween. The Pen/Gen/Res control 64 is variablebetween “Pen” (maximum penetration) and “Res” (maximum image resolution)and proportions of these maximum settings therebetween centered around anominal general setting “Gen”. The effect of the current setting of eachcontrol is shown by a marker 66 in the bar, which is positioned inaccordance with the effective setting currently applied to theultrasound images. An arrow 68 can be adjusted by a user pointing devicesuch as a trackball or key or mouse on the control panel 150 to manuallyset a control setting.

The Res/Speed control and the Pen/Gen/Res control can be independentlyset for either manual control or automatic control. When a control isset for manual control its setting can only be adjusted by manualmanipulation of the user. When a control is set for manual control itsmarker 66 is greyed out and moves in tandem with the constantly alignedarrow 68 as the user adjusts the arrow to vary the control setting. Whena control is set for automatic operation its marker 66 is brightlydisplayed and the arrow 68 and the marker can move independently. Whenthe user manually adjusts the arrow 68 in the automatic mode, the imagewill vary in response to the manual variation and the marker 66 willalign with the last setting of the arrow. Once manual control of thearrow is released, automatic operation commences. As the motion and/ornoise characteristic of the image field is detected and used todetermine appropriate automatic settings for the Res/Speed controland/or the Pen/Gen/Res control, the marker 66 will move automatically toshow the current setting resulting from automatic control. The user cansee at a glance how the automatic setting has changed from his or herlast manual setting, and can see the response of the control setting tothe motion and noise detected in the image field.

If the user is dissatisfied with the response of the automatic operationof a control, the user can reset the position of the arrow 68 of thecontrol. Resetting the arrow during automatic operation will reset thebalance of the respective performance factors of the control and willalso adjust the manner in which the automatic adjustments discussedbelow are made. For instance, if the user resets the arrow toward moreresolution (Res), the subsequent automatic adjustments can more greatlyfavor changes in the direction toward a greater Res setting. Resettingthe manual adjustment arrow of the controls can thus adjust the degreeto which the automatic system balances the competing effects ofresolution, frame rate, and depth of penetration.

Motion-detecting capabilities are often found in ultrasound systems fora variety of purposes. Various sensors have been used to detect themotion of an ultrasound probe, such as those described in U.S. Pat. No.5,529,070 (Augustine et al.) and U.S. Pat. No. 5,538,004 (Bamber).Motion may also be sensed by comparing successive real time images asdescribed in U.S. Pat. Nos. 6,299,579 (Peterson et al.); 6,238,345(Wissler et al.); 6,117,081 (Jago et al.); 5,782,766 (Weng et al.);5,575,286 (Weng et al.); 5,566,674 (Weng); 5,899,861 (Freimel et al.);5,910,114 (Nock et al.); and WO 00/24316 (Hossack et al.) The motionsensing or image alignment techniques described in these patents areused for purposes such as aligning individual images to create apanoramic image or to remove motional distortion from images. Any one ofthese techniques can be used in an automated system of the presentinvention. In an embodiment of the present invention the motion oralignment information is used to adjust the Res/Speed setting. Higherimage quality and a lower frame rate setting is employed when motion isrelatively low, and lower image quality and a higher frame rate isemployed when motion is relatively high.

An embodiment of an automated control of the present invention can startwith a sequence of ultrasound images such as image 70 in FIG. 3. Eachimage is analytically divided into a plurality of blocks 72 of apredetermined pixel size, such as 8 pixels by 8 pixels or 16 pixels by16 pixels. For a rectangular image the blocks may be oriented in arectilinear grid pattern. For a sector image such as image 70 of FIG. 3the blocks can be arranged in a curve-linear fashion according to thecurvature of the sector. Motion is then computed between correspondingblocks of successive images, as shown in FIG. 4. In this illustration ablock 82 of pixels in Img 1 acquired at one point in time is comparedwith the neighborhood of a corresponding block 84 of an image Img 2acquired at a different point in time. The next motion computation usesthe block 84 in Img 2 and a corresponding block 86 in image Img 3acquired at another point in time. For each block a motion vector can bederived by finding the maximal Pearson correlation between the two pixelpatterns. The formula for this computation is:$\rho = \frac{\sum\limits_{x,y}{\left( {{I_{t\quad 1}\left( {x,y} \right)} - {\overset{\_}{I}}_{t\quad 1}} \right)\left( {{I_{t\quad 2}\left( {{x + d_{x}},{y + d_{y}}} \right)} - {\overset{\_}{I}}_{t\quad 2}} \right)}}{\sqrt{\sum\limits_{x,y}\left( {{I_{t\quad 1}\left( {x,y} \right)} - {\overset{\_}{I}}_{t\quad 1}} \right)^{2}}\sqrt{\sum\limits_{x,y}\left( {{I_{t\quad 2}\left( {{x + d_{x}},{y + d_{y}}} \right)} - {\overset{\_}{I}}_{t\quad 2}} \right)^{2}}}$

where I(x,y) is the pixel intensity at coordinates (x,y), the indices t1and t2 indicate image frames at different time point, I is the averageintensity in the pixel block, and (d_(x),d_(y)) is the magnitude(distance) and direction of the local motion between two image frames.The correlation value ρ indicates the reliability of the motion vector(d_(x),d_(y)).

The motion vectors and/or correlation coefficients for a plurality ofblocks are then examined. The motion vectors and/or correlationcoefficients for all of the blocks can be examined, or only a selectedset of blocks can be used such as those in the center of the image 70.If the magnitude of the motion vectors is large for most blocks, or thecorrelation value ρ is low for most blocks, the frame rate is increasedby incrementing the setting of the Res/Speed control from Res towardSpeed. The resultant command from the motion/noise processor 46 to thecentral controller 28 causes the central controller to change thecommands to the probe 12 in a manner which increases the frame rate. Oneway to do this is to increase the angle or spacing of the beam steeringbetween adjacent beams through a change to the beam steering parameterT_(st). With the beams more widely spaced, fewer beams will betransmitted in the area or volume scanned by the probe which causes theframe rate to increase. That is, with fewer beams to transmit andreceive to acquire a frame or volume, the image area can be scanned inless time. The increase in the beam spacing decreases the spatialsampling of the image area or volume, causing a corresponding decreasein image resolution. Another way to do this is to increase the multilineorder: instead of receiving one or two receive beams in response to atransmit beam, the point spread function can be changed to receive twoor four receive beams in response to each of a lesser number of transmitbeams. Yet another possibility is to reduce the number of focal zones ofthe image. For instance, each pair of consecutive focal zones can becombined into one focal zone, with the focus set at the boundary of thetwo original zones. Thus, the Res/Speed setting has been adjusted in adirection which tends to increase frame rate (Speed) but with decreasedimage resolution (Res).

Correspondingly, if the magnitude of the motion vectors is small formost blocks, or the correlation value ρ is high for most blocks,indicating little motion between images, the image quality is increasedby changing the setting from Speed to Res. The command from the motionprocessor 46 to the central controller 28 now effects an increase in thebeam density by changing the beam steering parameter T_(st) to transmita greater number of more closely spaced transmit beams which areproperly received by a change of the receive beam parameter R_(st). Themultiline order can also be decreased from four to two or two to one,for instance, for a greater number of transmit beams. The number offocal zones can also be increased by splitting one or more current focalzones into two. These changes will all effect an adjustment of theRes/Speed setting in a direction which tends to increase imageresolution (Res) with a decrease in the frame rate (Speed).

As these adjustments are made the position of the marker 66 is changedaccordingly in the Res/Speed bar 62. This is generally done by changingthe value for the marker which is sent from the motion/noise processor46 to a graphics processor (not shown) which processes the graphicoverlay of the Res/Speed control for display with the ultrasound image.

A similar approach can be used to automatically adjust the Pen/Gen/Rescontrol 64 setting as a function of image signal/noise. FIG. 5illustrates the decorrelation of pure speckle images with motion. Thisplot is made of the change in correlation as a planar imaging probetravels in the elevational direction. As it does so and the image planemoves in the elevational direction, the speckle information begins todecorrelate over the entire image. In FIG. 5 the X-axis is the distanceof travel of the probe in mm and the Y-axis is the correlation betweenimages. The different curves represent the change in correlation atdifferent image depths shown by the legends in box 94. It can be seenthat the correlation changes at different rates, depending upon imagedepth. The solid line curves indicated at 90 for near and mid-fielddepths show a smooth decline in correlation as the image plane travels,gradually decreasing with increasing distance. However, the dashedcurves indicated at 92 for the far field (greater depths) are marked bya sharp drop with a small change in distance, followed by a more gradualdecrease. This large initial drop in correlation is believed to becaused by the decorrelation of electronic noise (signal/noise) in thefar field and directly related to imaging penetration. A response to asharp drop in correlation is an adjustment of the Pen/Gen/Res settingtoward increased penetration (Pen), as for example by decreasing thetransmit frequency or switching from harmonic frequency reception tofundamental frequency reception. See, by comparison, U.S. Pat. No.6,458,083 (Jago, et al.) and U.S. Pat. No. 6,283,919 (Roundhill et al.)By aligning consecutive image frames through motion compensation andcomputing the image decorrelation, an appropriate adjustment can be madeto the Pen/Gen/Res control to render the best image resolution withoptimal imaging penetration. This feature is particularly useful whenthe clinician is frequently changing the imaging depth during scanning.

Turning again to FIGS. 3 and 4, the correlation is computed for aplurality of pixel blocks 72 of consecutive images. The correlation inthe far field is compared with the correlation in the near and/or midfield or the correlation for the entire image. If the correlation isrelatively low in the far field and the correlation is relatively highelsewhere, the penetration is increased by adjusting the Pen/Gen/Rescontrol from Res or Gen toward Pen. This effects a command from themotion/noise processor 46 to the central controller 28 which causes thecentral controller to command a change in the operating frequency. Thiscan be effected by changing the transmit frequency parameter f_(tr) to alower transmit frequency, reducing the passband of the digital filter34, or a combination of the two. If blended fundamental/harmonicinformation is used in the far field, the blending ratio of the twotypes of signal content can be adjusted in favor of more fundamentalsignal frequency content. Alternatively, more pulses can be transmittedin each beam direction and greater signal averaging employed.Corresponding, the marker 66 of the Pen/Gen/Res control bar 64 isadjusted toward the Pen end of the control on the displayed graphic.

Similarly, if the correlation is relatively high throughout the image,that is, is not particularly low in the far field, the operatingfrequency can be increased to increase resolution, and the Pen/Gen/Rescontrol is adjusted from Pen or Gen toward Res. The motion processorcommands the central controller 28 to increase the operating frequencyby increasing the value of the transmit frequency parameter f_(tr),increasing the passband of the digital filter 34, or both. If blendedfundamental/harmonic information is used in the far field, the blendingratio of the two types of signal content can be adjusted in favor ofmore harmonic signal frequency content. A corresponding adjustmenttoward Res is made to the marker 66 displayed in the Pen/Gen/Res control64.

In an embodiment of the present invention, more efficient computationmay be obtained by using fewer pixel blocks 72 and the sum of absolutedifference (SAD) algorithm. See U.S. Pat. No. 6,442,298 (Olsson et al.)Corresponding pixel blocks of successive images can be compared tocompute the motion (displacement) vector from block to block over thetime interval between the two images. Then, using this vector, one ofthe image is warped (aligned) with the other on either a local or globalbasis. See U.S. Pat. No. 5,566,674 (Weng). This alignment reduces thedecorrelation between images due to probe or tissue motion, leaving thesignal/noise (electronic noise) factor as a decorrelative effect. Thenumber of pixel blocks used in the alignment computation can be fewerthan the number used in the subsequent correlation analysis to reducecomputation time, if desired. The correlation of the aligned or warpedimages is then computed as described above to automatically adjust thePen/Gen/Res control setting.

1. A method for automatically adjusting the relationship between imageresolution (Res) and real time frame rate (Speed) of an ultrasoundsystem comprising: acquiring a plurality of ultrasound images over time;sensing the relative motion between temporally different ultrasoundimages; and increasing the image resolution and decreasing the framerate in response to relatively less sensed motion or decreasing theimage resolution and increasing the frame rate in response to relativelygreater sensed motion, wherein the ultrasound system includes aRes/Speed display of the relationship between image resolution and framerate; and further comprising automatically adjusting Res/Speed displayin correspondence with a change made to the image resolution and/orframe rate.
 2. The method of claim 1, wherein sensing comprisescalculating the correlation of the pixel content of temporally differentultrasound images, wherein a relatively high correlation corresponds torelatively less motion and a relatively low correlation corresponds torelatively greater motion.
 3. The method of claim 1, wherein sensingcomprises sensing relative motion with a probe motion sensing device. 4.The method of claim 1, wherein sensing comprises sensing relative motionby analyzing the image content of successive ultrasound images. 5.(canceled)
 6. The method of claim 1, wherein the Res/Speed displayincludes a user adjustable setting which enables a user to manuallybalance the relationship between image resolution and frame rate of theultrasound system.
 7. The method of claim 6, wherein manual adjustmentof the Res/Speed display adjusts the manner in which subsequentautomatic adjustments to the balance between image resolution and framerate will be made.
 8. The method of claim 1, wherein the frame rate ischanged by changing at least one of the transmit beam density, multilineorder, number of focal zones, or number of transmit pulses.
 9. Themethod of claim 8, wherein the image resolution is changed by changingthe spatial sampling of the image field.
 10. A method for automaticallyadjusting the relationship between image resolution (Res) and the depthof penetration (Pen) of an ultrasound system comprising: acquiring aplurality of ultrasound images over time; calculating the electronicnoise between temporally different ultrasound images; and increasing theimage resolution in response to relatively less electronic noise orincreasing the penetration in response to relatively greater electronicnoise.
 11. The method of claim 10, wherein calculating the electronicnoise comprises calculating the decorrelation of electronic noisebetween regions of successively acquired images.
 12. The method of claim11, wherein calculating the electronic noise further comprises comparingthe correlation of far field signals with the correlation of signalselsewhere in the images.
 13. The method of claim 12, wherein when thecomparison shows a relatively low correlation in the far field and arelatively high correlation elsewhere, the operating frequency of theultrasound system is automatically decreased, and when the comparisonshows a relatively high correlation in the far field and elsewhere, theoperating frequency of the ultrasound system is automatically increased.14. The method of claim 10, wherein increasing the image resolutioncomprises increasing at least one of the transmit or receive frequencyof the ultrasound system, and wherein increasing the penetrationcomprises decreasing at least one of the transmit or receive frequencyof the ultrasound system.
 15. The method of claim 10, further comprisingaligning the temporally different ultrasound images prior to calculatingthe electronic noise.
 16. The method of claim 10, wherein the ultrasoundsystem includes a Pen/Gen/Res display of the relationship between imageresolution and depth of penetration; and further comprisingautomatically adjusting Pen/Gen/Res display in correspondence with achange made to the balance between resolution and penetration.
 17. Themethod of claim 16, wherein increasing the image resolution comprisesincreasing an operating frequency of the ultrasound system; whereinincreasing the penetration comprises decreasing an operating frequencyof the ultrasound system; and wherein automatically adjusting thePen/Gen/Res display comprises adjusting the display toward Pen when theoperating frequency is decreased and adjusting the display toward Reswhen the operating frequency is increased.
 18. The method of claim 17,wherein automatically adjusting the Pen/Gen/Res display comprisesadjusting the display toward Pen when fundamental frequency operation isperformed and adjusting the display toward Res when harmonic operationis performed.
 19. The method of claim 17, wherein the operatingfrequency comprises at least one of the transmit frequency or thereceive frequency.
 20. The method of claim 16, further comprisingmanually adjusting the Pen/Gen/Res display to adjust the manner in whichautomatic adjustments to the balance between resolution and penetrationwill be made.
 21. An ultrasonic diagnostic imaging system comprising: aprobe including an array transducer; a transmitter coupled to applydrive signals to the array transducer; a receiver coupled to processsignals received by the array transducer; a display coupled to thereceiver which displays received ultrasound images; a sensor coupled tothe probe which senses relative motion in the image field; a Res/Speeddisplay responsive to the sensor which is shown on the display to depictthe relative balance between image resolution and frame rate, whereinthe transmitter is responsive to the sensor for adjusting the frame rateof the ultrasound images.
 22. An ultrasonic diagnostic imaging systemcomprising: a probe including an array transducer; a transmitter coupledto apply drive signals to the array transducer; a receiver coupled toprocess signals received by the array transducer; a display coupled tothe receiver which displays received ultrasound images; a sensor coupledto the probe which senses electronic noise in the image field; aPen/Gen/Res display responsive to the sensor which is shown on thedisplay to depict the relative balance between image resolution andpenetration, wherein the transmitter is responsive to the sensor foradjusting the penetration of transmitted drive signals.